andycost@att.net wrote:
> I took the head off my U20 to track down a knock. It
> turned out to be a rod bearing. I hung the chain on
> the "hook of death" while the head was off. I also
> rotated the crank a few times while removing the
> pistons. I painted the link on the chain that matched
> the guide screw on the cam gear. Here is my question.
>
> 1. Is it possible for the upper chain to skip a tooth
> on the jackshaft gear when I rotate the crank?
If you kept the cam gear in place in the chain and suspended it from the
bracket by using a 8mm
bolt, it shouldn't. If you removed the cam gear and just hung the chain from
the bracket, then
probably.
> I don't want to take the timing cover off if I don't
> have to.
>
> 2. Can the cam timing be set without taking off
> the timing cover?
> I was thinking about bringing it to TDC and theneyeballing the cam.
Sure. Just be careful. Set #1 piston at TDC, making sure the rotor in the
distributor is pointed to
the #1 spark plug lead. Set the camshaft so the two front lobes are "splitting"
the 12:00 position.
Make sure the slack is out of the "down" side of the chain before you drop the
head on. Put the head
on and see if everything lines up. WARNING: once you have the head bolted down,
don't attempt to
rotate the crank without bolting up the cam. If you do, the pistons will come
up and hit the valves.
> 3. Guide screw at 3:00 right?
No, 12:00. The timing mark is at 3:00.
> I loosened the cam to allow the valves to shut while I
> was polishing the combustion chambers. The cam
> rotated.
It's generally better to loosen the adjusters all the way down and remove the
rockers before
unbolting the cam tower caps. BTW, I hope you masked everything off before you
started grinding
(including all the water passages into the head). Otherwise you should probably
have the head
disassembled and thoroughly cleaned.
> 4. Can it be tightened back down in the TDC alignment
> or is it going to turn as I crank it down?
It'll probably rotate from the force of the rockers on the lobes. But that's
okay, you'll wind up
realigning it to the cam gear anyway.
> One last thing. The crank pulley has separated and is
> rubbing the pointer.
>
> 5. Is it possible for the timing marks to get askew
> in relation to the crank?
Yes, if the outer ring of the crank pulley has come loose from the center
section.
--
Gordon Glasgow
http://www.gordon-glasgow.org
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